The present invention relates generally to an amusement device, and more particularly to a pogo stick that is collapsible for compact storage and is adjustable for use by persons of various heights and weights.
Pogo sticks are amusement devices that have been known in the art for many years and provide fun and exercise, particularly among children and adolescents. An exemplary pogo stick of the type known in the art is illustrated in FIG. 1. The pogo stick 1 comprises a frame 2, a footrest 3, a pair of handgrips 7, a shaft 6 slidably coupled to the frame 2, and a mechanical spring 5. The spring 5 fits over the shaft 6 such that the bottom end of the spring 5 is coupled to the shaft 6 and the top end of the spring 5 is coupled to the frame 2 via a cross-member 8. A rubber pad 4 is provided at the base of the shaft 6. The user stands on the footrest 3 and holds the handgrips 7 while performing a vertical jumping motion in conjunction with the spring forces provided by the spring 5. When the rubber pad 4 impacts the ground, the shaft 6 is forced upward into the frame 2 thereby compressing the spring 5. The spring 5 then resiliently recoils to thrust the shaft 6 back downward from the frame 2 and propel the user upward into the air.
Pogo sticks known in the art are manufactured with a rigid unitary body whereby the grips and footrest are permanently attached to the frame through welding or other means. Due to their unitary structure, pogo sticks cannot be collapsed and therefore require a large amount of storage space and are cumbersome to transport.
Pogo sticks known in the art use a mechanical spring having a fixed stiffness. The fixed stiffness significantly limits the efficiency and enjoyment of the pogo stick for users whose body weight is not compatible with the particular stiffness of the spring. A mechanical spring can also undergo gradual softening as it is subjected to working cycles, thereby causing the pogo stick to become completely inoperable over time. A mechanical spring also gives rise to undesirable frictional forces that detract from the efficiency and enjoyment of the pogo stick. Furthermore, mechanical springs are typically manufactured from steel that can rust and corrode when exposed to moisture. Worse yet, mechanical springs are subject to fatigue failures, which can result in a serious injury to the user.
Pneumatic springs are known in the art and generally comprise a pressure cylinder filled with a gas and a piston that is axially contained within the cylinder. Over the years, various designs have been proposed for substituting a pneumatic spring into a pogo stick. However, the pneumatic spring pogo sticks that have been proposed heretofore are complex devices that involve a large number of components. The complexity of these pogo sticks has made them prohibitively expensive to manufacture and prone to mechanical failures. Furthermore, although some of the proposed pneumatic spring pogo sticks were intended to be adjustable to accommodate users of various weights, none of the proposed pneumatic springs provides a practical means for adjusting the spring stiffness.
The preferred embodiments of the present invention provide a substantially improved pogo stick that is collapsible into a small volume for easy transportation and compact storage while having a rugged construction that ensures high quality and durability. The preferred embodiments are also provided with an improved pneumatic spring of variable stiffness. Another feature of the preferred embodiments is the minimization of frictional forces in the spring mechanism to provide a very smooth and enhanced jumping motion. The preferred embodiments are adapted to be made of a lightweight material that is resistant to corrosion.
A significant feature of the pogo sticks constructed in accordance with the preferred embodiments of this invention is the ease of transportability. Because it can be collapsed into a small volume, the pogo stick can be easily carried in a backpack or by hand to virtually any location. This feature facilitates sharing the pogo stick with others and joining with other pogo stick users in simultaneous use.
In one aspect of the present invention, a collapsible pogo stick is provided generally comprising a handlebar, a grip portion, a footrest, and a pneumatic spring. The handlebar comprises two substantially parallel elongate members wherein each elongate member comprises an upper tube and a lower tube. The upper tubes are telescopically adjustable with respect to the lower tubes for accommodating users of different heights. Furthermore, the upper tubes can be completely inserted into the lower tubes to reduce the height of the pogo stick when not in use. The footrest is transversely mounted at the bottom end of the handlebar and comprises a middle platform section and two plates that are pivotally mounted to each side of the platform. The plates can be folded upward to reduce the width of the pogo stick when not in use.
In another aspect of the present invention, a short middle tube is transversely mounted at the top of the handlebar and two grips are detachably coupled to the ends of the middle tube. An elastic cord extends through the middle tube and connects the grips to prevent the grips from becoming separated from the middle tube.
In another aspect of the present invention, a pneumatic spring is mounted at the bottom end of the handlebar and comprises a hollow pressure cylinder filled with a gas and a piston that is axially movable within the cavity of the cylinder. A shaft is coupled to the piston and extends downward out of the pneumatic cylinder for engagement with the ground. A significant feature of the preferred embodiments of this invention is the ability to vary the mass of the gas in the cylinder to adjust the stiffness of the pneumatic spring. Another feature of this preferred embodiment is the minimization of frictional forces in the spring mechanism.
In another aspect of the present invention, the cylinder of the pneumatic spring is mounted at the bottom end of the handlebar between the lower tubes. In one embodiment, a fastening ring is coupled to the top end of the cylinder and extends around each of the lower tubes to securely attach the pressure cylinder to the handlebar.
In another aspect of the present invention, the elongate members are rigid members that are slidably engaged within brackets on the outer portion of the cylinder. The handlebar may be raised and lowered with respect to the cylinder by sliding the elongate members through the brackets.
In another aspect of the present invention, the middle platform of the footrest is provided with a threaded through hole for engagement with a threaded region on the lower exterior portion of the cylinder to further secure the pressure cylinder to the handlebar.
In another aspect of the present invention, the shaft of the pneumatic spring is formed with a hollow interior portion and a manual pump is provided in the interior portion of the shaft. The manual pump provides a self-charging mechanism for increasing the stiffness of the pneumatic spring. The pump mechanism comprises a pumping piston that is slidably contained within the interior of the shaft and a pumping rod coupled to the pumping piston which provides a means to move the piston. Because the pump is substantially self-contained within the shaft, the internal pump mechanism does not affect the size of the pneumatic spring.
In another aspect of the present invention, a manual pump is provided on top of the cylinder for increasing the mass of gas in the cylinder. The manual pump includes a pump handle that is used for reciprocal actuation of the pump piston to increase the mass of gas in the cylinder.
In another aspect of the present invention, the collapsible pogo stick is provided with a handlebar comprising only a single elongate member having a lower tube and an upper tube. The bottom end of the lower tube is mounted to the top end of the pressure cylinder. The upper tube telescopes into the lower tube to accommodate users of various heights and to reduce the size of the pogo stick when not in use. In one variation of this aspect, the telescoping elongate member is operatively connected to a pump mechanism on the cylinder. The upper tube is telescoped in and out of the lower tube to actuate the pump and increase the mass of gas in the cylinder.
In another aspect of the present invention, a buffer sleeve of an elastic material is provided at the bottom end of the shaft for improved traction and to cushion the impact while jumping. The buffer sleeve may also serve to protect a self-charging pump mechanism contained within the shaft of the pneumatic spring.
In another aspect of the present invention, the mass of gas in the cylinder can be adjusted using a two-way valve mounted on the cylinder. The two-way valve can be attached to a pressurized source of gas or an external manual pump. The two-way valve also provides a means to rapidly discharge the gas from the cylinder.
In another aspect of the present invention, the piston can be fully advanced into the interior of the cylinder by completely discharging the gas from the cylinder. This aspect further reduces the size of the pogo stick when not in use.